In the present study, a convenient and highly efficient method was developed to quantify aflatoxin B (AFB) in oil samples. Low temperature clean-up (LTC) followed by immuno magnetic solid phase extraction (IMSPE) was used to clean up oil samples. LTC assisted in freezing out the interference from the oil matrix while IMSPE further helped to preconcentrate the targeted analyte. For IMSPE, we synthesised and characterised anti-AFB monoclonal antibody-functionalised magnetic nanoparticles. Oil sample extraction was then carried out using LTC-IMSPE. The proposed method showed satisfactory efficiency and reproducibility with recovery rates being within the range of 79.6-117.9%, with a relative standard deviation below 11.48%. The sensitivity of the method was satisfactory with the limits of detection and quantification being as low as 0.0048 and 0.0126 ng·g, respectively. Real sample analysis was carried out for five kinds of different vegetable oils. The results suggest that the method developed is very sensitive and accurate.